Accelerators



Patented Aug. 14, 1945 UNITED STATES PATENT OFFICE ACCELERATORS George W. Watt, Austin, Tex., assignor to Wingfoot Corporation, Akron, Ohio, a corporation of Delaware No Drawing. Original application June 29, 1938, Serial No. 216,627. Divided and this application June 19, 1943, Serial No. 491,567

14 Claims.

which may be prepared in the form of its salt from phenyl hydrazine, carbon disulfide and a hydroxide in the following manner:

@NH-Nm as, KOH

Other thiodiazoles may be prepared in the same manner, such as those in which the phenyl substituent of the foregoing compound has been replaced by tolyl, xylyl, naphth'yl, cumyl, and the like.

These amine salts of z-mercapto 4-aryl thiodiazole 5-thiones have been found useful as activators for accelerators of the vulcanization of rubber and may be employed in conjunction with mercaptobenzothiazole and other accelerators commonly used in rubber. The general formula for the class of activators herein described may be represented as follows:

where R is an aryl group and R1 and R2 may be aliphatic, aromatic or heterocyclic groups'or hydrogen, not more than one hydrogen being present. Furthermore, R1 and R2 may constitute, c'om'ointly with the imino or nitrogen containing group, a heterocyclic nucleus, such as the piperiphenyl cyclohexylamine,

dyl group. Where guanidine salts are formed, a special case arises under the general formula ven above which may be represented by the subgeneric formula:

R--NN so (")-SNHC/ NHR.

where Re. and Rs are simple or substituted ali- 'phatic, aromatic or heterocyclic groups or hydrogen. It will thus be seen that the mercapto compound may be reacted with compounds of the general formula in which R1 and R2 are hydrogen, aliphatic or aromatic radicals or, with the iminoor NH group, constitute a heterocyclic or a guanidine radical.

Among the various amines with which the 2- mercapto 4-aryl thiodiazole 5-thione may be reacted are cyclohexylamine, benzylamine, piperidine, dicyclohexylamine, dibuty1amine, N-ethyl cyclohexylamine, N-butyl cyclohexylamine, N-

dibenzylamine, betaphenyl ethylamine, N-butyl beta phenyl ethylamine, primary butylamine, amylamine, furfurylamine, tetrahydrofurfurylamine, difurfuryl amine, ditetrahydrofurfurylamine and N-cyclohexylfurfurylamine. Th guanidines form salts in a similar manner and are included within the term amine as used in the appended claims. Among the guanidines found suitable are diphenylguanidine, ditolyl guanidine, dixylyl guanidine, N-phenyl N cyclohexyl guanidine, N N dicyclohexyl guanidine, N-methyl acyclohexyl N tolyl guanidine, N-butyl N tolyl guanidine, phenyl tolyl guanidine and other similar guanidines.

The amine salts maybe readily formed by permitting the thiodiazole to'react, preferably in solution, with the selected amine or guanidine. The conditions for the reaction are not critical, room temperature usually being sufficient ,but the reaction mixture may require to be slightly warmed under reflux or, where heat is evolved, cooling may be necessary. The starting materials will ordinarily react in molecular or equivalent proportions but an excess of either one may be present where this is advisable in order to promote the reaction. The following examples illustrate a method of formation of these compounds, although it will be understood that the invention is not limited thereto.

Example 1 The piperidine salt of 2-mercapto 4-phenyl thiodiazole 5-thione was prepared from parts of the mercaptan dissolved in 50 parts of acetone at room temperature and treated with 618 parts of piperidine (10% excess). Heat was evolved and a white crystalline solid separated. The. mixture was cooled, diluted with parts of petroleum ether, filtered and the solid washedlwitli: petroleum ether and air-dried. The yield amounted to 20.5 parts of the piperidinesalt in; the form of a white crystalline solid; melting point 156-7 C. This corresponds to a theoretical yield. Analysis: Calculated for; GiaHi'zNzisizs} 30.86. Found: S, 31.16. Hence,- the-formula is assumed to be 06am r r cnr-cn s10 o-s-N, one

s H- GEM-CH2 Example 2" The cyclohexylamine salt was prepared by dissolving 15 parts of 2-mercapto 4 phenyl thiodiazole 5-thione in 50 parts-of acetoneat room temperature andtreating this with-7.2 parts of cyclohexylamine (10% excess) dissolved in 10 parts of acetone: reaction mixture-was cooled in' an ice bath and diluted-with ether and petrol'eum ether" to induce" crystallization: of the cyclo'hexylamine salt. Fl"- nally, the pale tan crystals which separated-werefiltered oif, washed with petroleum ether and dried. There were thus obtained 19.2 parts of the desired salt, a 90% yield. The melting point was l80-l81 C. Analysis: Calculated for C14H19N3S3:

S, 29:53... Eound:..S,-.30.-'0'7'v Hence, theiformula isi.

Other salts may beprepa-red'; in a manner sim=- ilar to=that set forth in the'f'oregoingex-amples; from the various 2-mercaptoary-l thiodiazol'ei B-thiones'. andithe various-amines; including: the: guanidines 'mentioned hereini I Certain of the'compoundswere' testedin rubber:

'I'he'various salts'were' added'to the stock inthe' amount indicated, these saltS' being identified as follows:

Name

'Pitpheridine' salt of 2 mercepto' #pli'enyl'thiodizizdl 5- 10118;, Cyclohexylaminesalt of 5'-thioire. ,Benzylamine; salt 01 .2.-mercapto. 4=plienyl thiodiazole S-thione.

Dicyclohexylann'n'e salt'of'2-mercapto 4-plieny1 thiodiazole S-thiona.

Sym. diphenylguauidine. salt of Z-mereapto 4-phenyl 2-mercapto 4-phenyl thiodiazole thiodiazolefi-thione.

An exothermic reaction-ensued-andthe- The results obtained as a result of testing these stocks after cure are shown below:

I Modulus No. Cure mins. gigg Ultimate at at F. kgSJcmJ elong.

Itwillbe noted that satisfactory cures, as indicated'.bythephysicalstrength, were obtained in other accelerators commonly used in.- rubber manufacture. While. certain preferred. formsof the invention have been;described.in detail, it;wil1- be apparent tothose skilledinthe ar.t .that.-vare ious.v modifications; and. changes may, be made: therein without departingfrom-thespirit of. invention or from the scope of the appended.- claims wherein it is intended to cover all features of patentable novelty residing in such invention.

I claim:

1. A method of treating rubber which comprisesvulcanizing it in the. presence of. an amine salt; of a. 2-me'rc'apt 4l-aryl. tjili iodiazoliel fi-thione: in which the amineisselected from. thergraup consisting of aliphatic amines, aromatic substi tuted aliphatic, amines, alicyclic amines, and guanidines.

2. A method of treating rubber which comprises vulcanizing it in\ the presence of an amine salt of a 2-mercapto 4-phenyl thiodiazole 5-thione in which theamine is selectedirom the group. consisting of aliphatic amines, aromatic substi tuted aliphatic amines, alicyclic amines, and

' uanidines.

3. A- method of treating rubber which comprises vulcanizing it in the presence of an aliphatic amine salt of a 2-mercapto 4-phenyl thin.- diazole 5'-thione.

4. A method of treatingI rubberjwlii'cli, com.- prises vulcanizing itinthe presence, of an. aralliyl' amine salt of a 2+mercapto 4-aryl thiodiazolc: 5-thione.

5'. A method of, treating rubber, which. comprises vul'canizing itin the presence of acyclohexyl amine salt offz-mercapto 4'-plienyl thiodiazole B-thione. i

6. A method oftreatingfirubber which; comprises vulcanizing'v it in. the presence of. a benzyl' amine salt of 2-mercapto;4'-phenyl".thiodiazole 5-thione.

7. A rubber product which hasbeen vulcanized in the presence of an amine salt: of a 2-mercapto 4-aryl thiodiazole 5-thionein which the amine is selected from thev group consisting of aliphatic amines, aromatic substituted aliphatic amines; alicyclic amines, andguanidines; Y j

8. A rubber product which has beenvuloaniwi in the presence ofan amine saltof a 2 mercapto 4-phenyl' thiodiazole 5-thione in which the is'selected'from the group consisting of'aliphatic 12. A rubber product which has been vulcanized amines, aromatic substituted aliphatic amines, allcyclic amines, and guanidmes.

9. A rubber product which has been vulcanized in the presence or an aliphatic amine salt of a. 2-mercapto 4-phenyl thiodiazole fi-thione.

10. A rubber product which has been vulcanized in the presence of an aralkyl amine salt of a Z-mercapto 4-ary1 thiodiazole 5-thlone.

11. A method of treating rubber which comprises vulcanlzing it in the presence of the amyl amine salt of 2-mercapto 4-pheny1 thiodiazole 5-thione.

GEORGE W. WATI. 

